Conventional practice for most architectural precast concrete cladding systems requires a labor and material intensive full masonry application. Examples of such architectural cladding systems would be manufactured stone, stucco, and either cementitious or hard-coat, synthetic stucco also known as Exterior Insulation Finish Systems (EIFS), and concrete or clay brick cladding. These practices necessitate a 2-3 step sequential process requiring prep or scratch coat, a separate wire mesh, or lath affixed to the prep coat, and finally a bed of mortar to set and adhere the cladding material to the structure. This 2-3 step method requires the contractor to mobilize and demobilize the labor force and equipment twice or more for the same job. This is due to the need for the initial prep or scratch coat to dry and set up for 48 hours prior to completing the stone, stucco, or brick installation. Some applications could require multiple prep coats. A major problem with these cladding systems is the absence of an engineered drainage gallery or rainscreen to deflect moisture away from the cladding and structure.
Additionally, the absence of airspace for ventilation between the cladding and the structure is a deficiency. These deficiencies are the precursor to the development of mold and dry rot, which threatens the health of the occupants and the value of the structure. Another limitation of the above cladding systems is that the masonry material or mortar is only as good as how it is mixed on the jobsite. Mixed or applied improperly the mortar is subject to cracking and failure, causing the cladding system to fail and possibly fall off the building. Brick and stone systems are also much thicker in volume and heavier in weight. This increases costs for production, handling and transportation. Conventional masonry practice is also vulnerable to the elements, which prevents the installation during inclement conditions. The cladding systems could further be compromised by a sudden change in the weather during the installation, or 48 hours after completing the installation while the mortar is setting up to material strength specifications. The reality is that conventional mortar by its very nature is permeable, even mixed and applied properly under the right weather conditions, and is subject to predictable degradation from the elements.
An improvement to such practice and cladding systems is disclosed in U.S. Pat. No. 6,253,515 to Kuelker, 2001 Jul. 3. This patent employs a mortarless method for attaching a precast concrete cladding system with a mechanical connection, precluding the need for a full masonry application. A bead of caulking is applied to the joints to complete the cladding system. However, this prior art suffers from several disadvantages which limit its functionality, durability, constructability and mass production capability.
First, the hangars or connectors are designed to be cast-in-place on the back of the precast cladding units at point of manufacture only. There is no disclosed provision for anchoring or fastening connectors in the field after manufacture. This limitation impacts the mass production of the system for precast manufacturers with automated or robotic production processes. This in turn restricts achievable economies of scale required to manufacture the system in a cost efficient manner. Additionally this cast-in-place only option requires more labor and materials for packaging and transport of the system to the jobsite.
Second, the shape, profile, and gauge of the hangars or connectors per FIGS. 10, 11 and 14 of U.S. Pat. No. 6,253,515 referenced above, expose the system to damage during transport and handling in the field. Deformation of these hangars render the system vulnerable to total failure, as the structural integrity of the hangar is the sole means for connecting the cladding to the building.
Third, the dimension of the drainage gallery that results from the profile of the hangar is inadequate for wetter climates and coastal regions.
Fourth, there is no claimed means for providing automatic alignment and self-leveling features for the installers, who then have to make these adjustments manually on site.
Fifth, there is no provision for panelizing the system, thereby allowing the system to be cast in larger panel dimensions, with architectural façade joints that give the appearance of several individual tiles or units, but are in fact cast as one single panel. This limitation further hinders achievable manufacturing, shipping and installation efficiencies.
Sixth, there is no reference to the utilization of recycled materials such as fly ash, coal combustion by products, and recycled glass fibers in the manufacture of the system. Thereby addressing several economic and environmental concerns, given dwindling stocks and rising costs of Portland cement. Additionally obstructing the ability for the producer to achieve stronger compressive material strength, lighter material weights, and the reduced carbon footprint of fly ash cements compared to production of conventional Portland cements.
Seventh, there is no claimed means for a cladding system that can absorb post construction settlements, thermal expansion and certain seismic activity. Eighth, there is no disclosed provision for a monolithic structural/architectural wall assembly. Whereby, the cladding system can be preassembled in the factory, or sandwich style rapidly on site to a structural wall component, such as tilt-up precast walls, or the new prefabricated structures and homes. Thereby preventing the need for two separate wall components or applications, to provide one wall assembly as with conventional building practice.
Finally, there is no provision for a cladding system, given its mortarless nature, which can incorporate an ultra thin and lightweight solar film cell embedded in the precast units to regenerate the power of natural sunlight into functional energy sources.
Consequently, there is a need in the industry for a mortarless modular architectural precast cladding system that is an improvement to the prior art, and overcomes the limitations and disadvantages of this prior art as outlined above.